"I believe the ix-4x90k chips have soldered lids instead of TIM, which means assuming the silicon is the same, you can get much better OCs out of an i7-4790k than an i7-4770k."
I have delidded a few 4790K and they are definitely not soldered. The TIM is a different consistency and color that that in 4770K, and works a little better. Not enough better to avoid delidding for serious benchmarking.
The Extreme Editions X9xx ranging from 3920K - 3960X - 4920K - 4960X that run in 2011 sockets are soldered. Intel has said that the Haswell Extreme - 5920K, 5930K and 5960X are lidded with thermal epoxy. They might not be as good as the soldered ones, but they can't be delidded without destroying the chip.
4790K vs Haswell Extreme vs waiting for Broadwell is a matter of your choice, JimmyH. If you want it now, you'll have to do without Broadwell. If the budget precludes Extreme Editions, I think the 4790K is the best you can do.
Jeff